20.4 Distinguish Interactive Calls

Sometimes a command should display additional visual feedback (such
as an informative message in the echo area) for interactive calls
only. There are three ways to do this. The recommended way to test
whether the function was called using call-interactively is to
give it an optional argument print-message and use the
interactive spec to make it non-nil in interactive
calls. Here's an example:

We use "p" because the numeric prefix argument is never
nil. Defined in this way, the function does display the
message when called from a keyboard macro.

The above method with the additional argument is usually best,
because it allows callers to say “treat this call as interactive”.
But you can also do the job by testing called-interactively-p.

— Function: called-interactively-p kind

This function returns t when the calling function was called
using call-interactively.

The argument kind should be either the symbol interactive
or the symbol any. If it is interactive, then
called-interactively-p returns t only if the call was
made directly by the user—e.g., if the user typed a key sequence
bound to the calling function, but not if the user ran a
keyboard macro that called the function (see Keyboard Macros). If
kind is any, called-interactively-p returns
t for any kind of interactive call, including keyboard macros.

If in doubt, use any; the only known proper use of
interactive is if you need to decide whether to display a
helpful message while a function is running.

A function is never considered to be called interactively if it was
called via Lisp evaluation (or with apply or funcall).